Which carbohydrate is known for being dietary fiber and is indigestible by humans?

Which carbohydrate is known for being dietary fiber and is indigestible by humans?

• A. Starch
• B. Glucose
• C. Cellulose
• D. Sucrose

Answer: (C)

Cellulose is the plant structural carbohydrate that humans cannot digest, so it passes through the digestive system largely intact and functions as dietary fiber. The reason is in the bonds: cellulose is made of glucose units linked by beta-1,4 glycosidic bonds, which human enzymes cannot break. This resistance to digestion means cellulose contributes to stool bulk and helps with bowel regularity. In contrast, starch is digestible because humans have enzymes to break the alpha-1,4 and alpha-1,6 linkages, glucose is a simple sugar readily absorbed, and sucrose is a disaccharide that is split into glucose and fructose by sucrase in the small intestine. Thus, cellulose best fits being dietary fiber and indigestible by humans.

Cellulose is the plant structural carbohydrate that humans cannot digest, so it passes through the digestive system largely intact and functions as dietary fiber. The reason is in the bonds: cellulose is made of glucose units linked by beta-1,4 glycosidic bonds, which human enzymes cannot break. This resistance to digestion means cellulose contributes to stool bulk and helps with bowel regularity. In contrast, starch is digestible because humans have enzymes to break the alpha-1,4 and alpha-1,6 linkages, glucose is a simple sugar readily absorbed, and sucrose is a disaccharide that is split into glucose and fructose by sucrase in the small intestine. Thus, cellulose best fits being dietary fiber and indigestible by humans.